As household and other wastes gradually decompose in commercial landfills, significant quantities of gases are generated as decomposition products. These include hydrocarbons, particularly methane, as well as carbon dioxide, nitrogen, water vapor, and other gases and hydrocarbons. If captured and recovered from the landfill site, the methane generated during landfill decomposition represents a potentially valuable energy or feedstock source, particularly if the methane is refined or purified in such a manner as to meet the quality requirements to be accepted for delivery in natural gas pipelines to customers as a substitute for natural gas obtained from drilled natural gas wells.
To be combusted and used as an energy or feedstock source, however, the methane must first be separated from the other landfill gases and substantially purified. Therefore, there is a need for improved methods and systems to separate landfill gases, particularly methane, from other components of landfill gas streams so as to provide a substantially purified methane stream which may be either combusted and used as an energy source or used as a feedstock for the manufacture of other chemicals or substances.